Summary: The reason why the E154F Transmission, is the best choice for a 3SGTE gen4 Rav4 swap is because the gearbox features better gear ratios for faster acceleration, dual cone synchros, but most importantly it has a VSS (vehicle speed sensor) in exactly the same location as the E250F Rav4 gearbox, meaning the speedometer will work with the same electrical connector as the Rav4.

Summary: The Caldina gets its speedometer reference signal through the ABS Computer, there no electrical plug on the gearbox, there is also no gear ring inside of the transmission. You can use a Dakota Digital SGI-5E Speedometer Interface, connected to any working ABS Wheel Speed Sensor using shielded wire to provide your OEM Speedometer a signal that will work. You will LOSE ABS FUNCTIONALITY. You cannot "tap or split into" the ABS signal, otherwise both the vehicle ABS and the Speedometer will fail to work. If you want to ditch ABS like I did, you'll be fine using the Caldina E150F transmission with Dakota Digital SGI-5E and dealing with an ABS Light (if its legal in your area). The Caldina Gearbox, like the Celica GTfour both require CALDINA Axles left and right to work in a Rav4 Swap, however, the RIGHT SIDE CELICA/CALDINA INNER axle joint is identical in shape and size of the RIGHT SIDE rav4, CV Axle just weaker in design. the inner axle joint is designed differently and cannot be joined together, and the Celica axle is too long for the Rav4.

Summary: Your existing Rav4 manual gearbox and axles WILL fit the Gen4 3S-GTE engine, however, The reason the originally installed Rav4 AWD E250F manual gearbox is the worst choice, is because the gear ratios are intended for the 3s-FE Engine, which is only 98-105HP. The 3S-GTE after a good exhaust upgrade and boost increase is ~280-320HP. Your engine will rev at ~5,500RPM in 5th gear on the highway which is loud and annoying. Those who have done this but used really big tires say its not so bad drive about, or below the speed limit.

TL;DR You will not get the full potential of your 3S-GTE upgrade, without 3S-GTE rated gearbox (E154F/E150F)